Rectal Quetiapine for Delirium in Patients with Advanced Cancer: A Retrospective Observational Study

Background: Rectal administration of antipsychotics is an alternative approach for treating delirium in patients with advanced cancer who are unable to take oral medications. Objectives: Characterization of patients treated with quetiapine suppositories (QSP) and determination of its efficacy and safety. Design: Retrospective observational study. Setting/Subjects: Patients with advanced cancer who died in a Japanese palliative care unit (QSP group, n = 421; non-QSP group, n = 442). Measurements: Delirium severity scores (DSSs; sum of scores for items 2–4 of the Nursing Delirium Screening Scale), use of antipsychotics and benzodiazepines, adverse events (AEs) during the last week of life, and overall survival in both groups. DSSs and AEs following QSP administration in the QSP group. Results: The QSP group more frequently exhibited delirium on admission than the non-QSP group (22% vs. 15%, p = 0.001). Higher DSSs and frequent antipsychotics (90% vs. 30%, p < 0.001) and benzodiazepines (68% vs. 37%, p < 0.001) use were observed in the QSP group. The mean DSS was 1.8 (95% confidence interval: 1.6–1.9) before QSP administration, dropping to 0.61 (0.47–0.75, p < 0.001) 72 hours after administration. The incidence of hypotension (71% vs. 60%, p < 0.001) and apnea (25% vs. 17%, p = 0.004) was higher in the QSP group. There was no significant difference in median survival (QSP, 14 days; non-QSP, 13 days) after adjustment for patients’ background characteristics using propensity score matching. Conclusion: QSP administration alleviated severe delirium in our cohort, and associated AEs did not impact survival.